A floating skimmer for cleaning the surface of a body of liquid has been disclosed in U.S. Pat. No. 3,970,556 to GORE. This floating skimmer has an outer body with an inner cavity. Flotation and ballast chambers in the outer body are used to regulate the level of a flotation of a weir located within the body which regulates the flow of liquid into the met cavity from where it is pumped out via a pipe. The weir is movable and extends across the width of an inlet opening and regulates the flow of liquid into the inner cavity. The weir is pivotally hinged with a float on its underside. Therefore the weir floats on the liquid within the inner cavity and provides a cascade of liquid over the inner edge of the weir. The operation of the skimmer depends on the level of liquid within the inner cavity which varies according to the suction of the pump. The level of the liquid witch the inner cavity causes the buoyancy of the skimmer to vary during its operation and if not enough liquid from the liquid's surface cascades over the weir a loss of pulling effect can occur.
A pool skimmer for a swimming pool has been disclosed in U.S. Pat. No. 4,105,557 to WEATHERHOLT. This buoyant pool skier is powered by water pressure from a pump and is thus moved about on the surface of the water in the pool. As the skier moves about in any direction, a filter device is used to collect debris. The filter device remains within the pool during its use and therefore must be removed and cleared periodically to ensure efficient operation. The skimmer relies on the force of water passing over the filter device as it moves to collect the debris in the pool. This skier cannot be used continuously as it must be cleared regularly.
An oil collecting apparatus has been disclosed in U.S. Pat. No. 4,243,529 to STRAUSS. This apparatus has a two-part housing which defines an inner cavity and an annular opening in the side thereof. Oil is able to flow through an hydrophobic-oleophilic screen in the opening, however, water is prevented from flowing therethrough. The buoyancy of the apparatus is able to be adjusted depending on the thickness of oil. This device is inappropriate for removing debris located on the water's surface, as the pumping out system is intermittently operated by a buoyancy float.
A floating weir has been disclosed in U.S. Pat. No. 4,405,458 to McHUGH. The floating weir has a float which adjusts the level of the weir according to the internal water pressure within its floating device. The device is supposed to operate at a constant level but is able to respond to flow interceptions caused by water disturbances. This device relies on a float and if the flow interruption was greater than expected the device would not continue to operate as required.
A floating pool skimmer has been disclosed in U.S. Pat. No. 4,746,424 to DREW. This skimmer is propelled about the swimming pool whilst collecting leaves and other debris on the surface. The debris is directed downwards by water jets into a mesh bag. The device relies on the use of these water jets to clean the pool and for propulsion which requires extra piping and pumps.
Another skimmer has been disclosed in DE,A,2,435,881 to PEACOCK INVESTMENTS LTD. This skimmer includes a hollow unit, partially above the water's surface and a filter chamber between a water intake and a water outlet. The water moves through the skimmer as it moves about on the water's surface. This device has the disadvantage that it requires propulsion on the surface of the water.